mlxsw: spectrum_fid: Configure VNI to FID classification

In the new model, SFMR no longer configures both VNI->FID and FID->VNI
classifications, but only the later. The former needs to be configured via
SVFA.

Add SVFA configuration as part of vni_set() and vni_clear().

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>